1. Field of the Invention
The present invention relates to a chemical mechanical polishing(hereinafter "CMP") apparatus, and more particularly to a CMP apparatus in which a chemical mechanical polishing is performed at a wafer surface.
2. Description of the Related Art
Due to the recent developments in manufacture of semiconductors, semiconductor devices have been highly integrated. To achieve high integration in the semiconductor device, it is required to obtain photolithography margins or a planarization process at a bottom layer so as to minimize its wiring length. According to these requirements, the CMP method has been introduced as a known technology to planarize a bottom layer. Among the semiconductor manufacturing procedures, the CMP method is utilized at a step of planarizing the bottom layer formed on a wafer surface. In the CMP method, the wafer surface is chemical-reacted with slurry containing microscopic particles and the chemically reacted wafer surface is mechanically polished with a polishing pad.
The conventional CMP apparatus using slurry and polishing pad consist of a polishing pad rotating operator, a wafer holder that a wafer is fixed in, and a slurry supplier which supplies slurry on a wafer surface.
The conventional CMP apparatus as constituted above, however, incurs a disadvantage that pressure from the polishing pad to the wafer is locally different, and then the polishing thickness is not uniform.
Specifically, there is a strong possibility of transformation in the polishing pad since the polishing pad rotates and is contacted closely to the wafer surface. When the polishing pad is transformed, a dishing is occurred at the rotating polishing pad. Therefore, when the dishing is occurred at the polishing pad, should the polishing pad should be substituted at once. Due to the substitution, the realization of CMP process may be deteriorated during a polishing process using the new polishing pad.